Australian Open: Victoria Azarenka falls to Agnieszka Radwanska

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World No. 2 Victoria Azarenka had taken the women's title at Melbourne Park in each of the past two years.

Story highlights

Defending champion Victoria Azarenka beaten by Agnieszka Radwanska at the Australian Open

World No. 2 Azarenka has taken the title at Melbourne Park in each of the past two years

Fifth seed Radwanska will play Slovakia's Dominika Cibulkova in the semifinals

Cibulkova beat Romania's Simona Halep to reach the last four

The Australian Open is known as the "Happy Slam." The players are usually re-energized after the off-season and gush over the way the tournament is organized.

But for the fourth day in a row in Melbourne, a multiple grand slam winner left the tournament without a smile on their face.

Following Serena Williams, Maria Sharapova and Novak Djokovic, two-time women's defending champion Victoria Azarenka became the latest big name bundled out when the Belorussian fell to Agnieszka Radwanska on Wednesday.

Yes, the upsets keep coming.

Radwanska not only defeated Azarenka in the quarterfinals to snap a seven-match losing streak against the world No. 2 but she didn't drop a game in the third set of the 6-1 5-7 6-0 victory.

Photos:Bouchard the Belieber

Photos:Bouchard the Belieber

Now I'm a Belieber! – Eugenie Bouchard scored a shock victory over 14th seed Ana Ivanovic to reach the semifinals of her first Australian Open. The Canadian came back from one-set down 5-7 7-5 6-2.

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Photos:Bouchard the Belieber

Dream date – During her on-court interview Bouchard was asked who her ideal date would be. The 19-year-old said teenage pop star and fellow Canadian Justin Bieber.

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Photos:Bouchard the Belieber

Last legs – During the match Ivanovic received treatment on an injury to her left leg, while also revealing she had been struggling with a problem in her right leg throughout the tournament.

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Photos:Australian Open hots up

Photos:Australian Open hots up

Australian Open hots up – Li Na faced a battle to stay cool and to stay in the Australian Open against Lucie Safarova.

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Photos:Australian Open hots up

Medical treatment – Li's compatriot Zheng Jie needed medical treatment for heat stress during her 6-2 6-4 defeat by Casey Dellacqua. "I felt so hot, my mind wasn't working," said Zheng. "I was looking at the ball, but I couldn't focus on it. Then I couldn't concentrate. This weather is very difficult for me.

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Photos:Australian Open hots up

Sleepless nights – Serena Williams looked in complete control during her straight-sets win over Vesna Dolonc on Wednesday, but the top seed admitted to waking up in the middle of the night due to fears over dehydration.

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Photos:Australian Open hots up

Ice cool – Maria Sharapova wrapped ice around her neck in a bid to keep cool during her first round win over Bethanie Mattek-Sands.

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Photos:Australian Open hots up

It's a hot Juan – Playing early in the day on Tuesday, Argentina's Juan Martin del Potro felt the heat during his win over American Rhyne Williams.

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Photos:Australian Open hots up

Fainting – It all got to much for Canadian Frank Dancevic who fainted during his match with Frenchman Benoit Paire.

Exposed to the elements – While supporters in the Rod Laver Arena could at least take cover under its roof, fans on the outside courts were exposed to the elements.

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Photos:Australian Open hots up

Strike a pose – With temperatures exceeding 40 degrees Celsius at the Australian Open, sport scientist Dr. Ross Tucker suggests any player hoping to succeed Down Under should take up Bikram Yoga.

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Photos:Australian Open hots up

Hot shot – Men's fourth seed Andy Murray is a long-term practitioner of bikram yoga. Clearly comfortable in the heat, he's reached the final in Melbourne in three of the last four years, though the Scot has questioned if the players' health is being put at risk.

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Photos:Australian Open hots up

Beach party – While some chose to head to Melbourne Park, other Melbournians chose to hit St. Kilda beach.

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When Azarenka misfired to seal her fate on match point, the crowd at Rod Laver Arena roared its approval.

With Djokovic departing Tuesday at the hands of Stanislas Wawrinka, it marked the first time in the Open Era both the men's and women's defending champions in Australia were eliminated at the quarterfinal stage.

"I think about today's match, what I did, what I could do better," Azarenka told reporters. "But other players, different vibe, whatever, I don't really care about that."